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Services Performed � <br /> A visit to the Sundby residence was made by a Barr geotechnical engineer on May 17�', <br /> 2006.The purpose of the site visit was to collect information xegarding the general <br /> condition of the walls,perform soil borings with a hand auger, and evaluate the feasibility <br /> of various alternatives for replacing the existing wall. These aitematives include cast-in- <br /> place concrete,rnodular block,boulders,and another timber wall.Mr. Sundby's <br /> preference is a boulder wall,so this option was evaluated particularly. • <br /> Soil borings with a 5-foot hand auger were performed at three locations at the main wall. <br /> The first,refened to as HA-1, was performed about three feet away from the top of the <br /> upper tier wall.This hole was placed in line with one of the shallow wooden tie-backs to <br /> evaluate its integrity. The second hole,called HA-2, was placed about 3 feet southwest <br /> (pazallel to the wall)of HA-1.The purpose of this hole was to collect information about <br /> the type of backfill soil and the axnount of water present in the soil. The third boring, <br /> refenred to as HA-3,was performed in the backfill soil above the lower tier wall about 2 <br /> feet from the timbers of the lower wall. S oils encountered in the hand augez borings were <br /> classified accordi.ng to ASTM D2488. <br /> Results � <br /> Site Visit <br /> Logs of the hand auger borings are attached.As seen in the boring logs,HA-1 went to a ` <br /> depth of 1.8 feet before hitting refusal on wood and the other two terminated at a depth of <br /> 5 feet(the maximum reach of the hand auger).Photogra.phs of the final hand auger depths <br /> aze shown in Photos 3,4, and 5. The borings indicate that the backfill soils comprise a 6- <br /> inch layer of topsoil overlying si2ty lean clay with varying aiuounts of sand and gravel. <br /> The material becomes coarser with depth,especially at HA-3 where the soil is classified <br /> as sand with silt from a depth of 4 to 5 feet. No saturated soil was encountered,but was � <br /> classified as moist.The wood encountered in HA-1 was likely the timber tie-back. The <br /> wood of the tie-back appeazed to be in good condition because the samples that were <br /> recovered from the auger were zelatively well-preserved and the auger could not <br /> penetrate all the way through it. If the tie-back had been rotted,the auger should have <br /> been able to pass through without significant effort. <br /> The condition of the individual timbers on the face of the wall is poor.Although the ` <br /> timbers are treated,the wood has undergone moderate degradation due to wood rot. This <br /> is probably duz in part to the backfill soil behind the wall holding moisture next to the <br /> timbers. With the wood also having access to oxygen from the face of the wall,the <br /> timbers have been subjected to decay.Additionally,there is normal decay that occurs in <br /> timbers that are 20 or more years old. One result of the wood de�terioration is that some of <br /> the pins counectin� tiie face tim'oer�and espGC;iatly tt�ose joining`�'ue uz backs�a i11e iace <br /> timbers have had their effectiveness decreased significantly. In other words,the pins no <br /> longer have any wood material left to hold onto in some locations to tie the timbers <br /> together, as shown in Photo 6.The most observable evidence of this phenomenon is that <br /> the wall has moved forward relative to the tie-backs, which have remained stationary <br />